Sound absorbing construction



April 13, 1937. c. F. BURGESS 2,076,807

SOUND ABSORBING CONSTRUCTION Filed Dec. 19, 1930 Patented Apr. 13, 1937 UNITED STATES' PATENT OFFICE SOUND ABSORBING CONSTRUCTION Application December 1951930, Serial No. 503,543

13 Claims.

'I'his invention relates to improvements in sound-absorbing constructions and more particularly to a sound-absorbing construction having a perforated metal facing. It is directed especially to a sound-absorbing pad having a perforated metal foil facing secured thereto.

The R. F. Norris patent No. 1,726,500 of August 27, 1929, discloses a sound-absorbing construction in which a perforated metal sheet or other substantially non-sound-absorbing membrane, preferably rigid, is used as a facing for sound-absorbing material such as balsam Wool, hairfelt, porous ceramic products and the like. In the Norris construction the perforated facing material preferably is rigid enough to support the soundabsorber Without sagging. It is usually erected independently of the absorber which may afterwards be placed adjacent to it on the side away from the eye. 'I'he perforations are of such size and number that the imperforate portion of the surface exposes an apparently substantially continuous surface to the sound waves and one which may be decorated readily. To avoid the exposure of fastening means to the eye a supporting structure of furring strips is used in connection with the perforated metal units, which are preferably pan-shaped.

In my improved construction I retain some of the advantages of the perforated-metal-faced sound-absorbing construction but avoid the necessity of using an expensive supporting structure. My improved perforated-metal-faced soundabsorbing construction may be glued, nailed or otherwise fastened to walls, ceilings and other surfaces, as is done with hairfelt pads and other similar sound-absorbing blocks at the present time. The cost of this method of installation is comparatively low. Furthermore, my improved construction stiffens andv strengthens the soundabsorbing pads.

My invention is described in connection with theaccompanying"drawing in which:

Fig.` 1 shows a cross section of a pad made in accordance with one method of my invention;

Fig. 2 shows in cross section the details of the conbined punched foil and absorbing pad formed in the preferred Way;

Fig. 3 shows, on a larger scale, the punch used to form the preferred perforations.

5W" In my improved construction I utilize thin metal foil in most instances. Copper foil about 0.002 inch thick made by an electro-deposition process is now available and is used to advantage. Aluminum foil is also available and in lesser thicknesses. Zinc foil and tin foil arealso pro- 1 secured if desired in other ways.

. it has the disadvantage of rusting and being less corrosion resistant. The thickness of the foil used depends on its physical properties, availability, and cost per unit of area of surface covered. Although it is desirable to use the foil as thin as possible to lessen the cost of the soundabsorbing construction it is possible to use metal in thicknesses several times heavierthan the above 0.002 inch copper foil, the thickness being determined by the supporting strength of the underlying material against the perforating pres- Sure.

The sound-absorbing pad which is faced with the perforated metal may be any sound-absorbing material which maybe formed into panels or pads and which has enough cohesion so that the facing may be attached thereto and made integral therewith. Loosely bound hairfelt is unsuitable because of the poor cohesion. When the metal foil ismounted on it by gluing or by the perforating operation to be described, it is torn off easily. A sound absorber of the structure of insulating building boards and similar materials is especially suitable. Sound-absorbing tile made by cementing packed asbestos, mineral wool, or the like together into a porous form also are suitable. Certain types of plaster and ceramic soundabsorbers may also be used.

In the simplest form of my invention the soundabsorbing material I0 is faced with the perforated metal foil sheet Il. 'Ihe size and number of the perforations I2 is in accordance with the description in the Norris patent. The metal foil, after perforating, is coated with a suitable adhesive and caused to adhere to the face of the pad or The foil may extend beyond the face of the pad and be made to cover the edges of the pad as shown and may be secured thereto in various ways. This adds to its appearance and gives added strength. Also, said foil conforms to the surface to which it is caused to adhere, whether the same is at or otherwise formed. I'he perforated foil facing does not decrease the sound-absorbing quality of the tile, provided of course that the glue or other adhesive is not allowed to coat the absorber opposite the perforations in the/,foil and thereby prevent the sound waves from entering the interior of the pad. The gluing operationmakes the Y foil integral with the sound-absorbing pad.

The preferred form of my invention is made bypiacing the unperforated metal foil on the face of the sound-absorbing pad. The foil may be glued to the surface though this it not necessary. The foil is then perforated so that the metal displaced is not sheared `o but. forms tangs I3 which are forced into thesoundvabsorber I4 as shown greatly enlarged in Fig. v2.

If the punch used is properly designed, the form of the tangs can be controlled, that is. they may be made of any predetermined size 'and shape. The tangs maybe anchored in the abv sorber asl shown, It is apparent that if the metal foil is not hard or stienough the tangs cannot be forced into the absorber.

'I'he preferred type of punch necessary to control the tangs without distorting and tearing the foil irregularly is described and claimed in Patent 1,a3'1,4511ssued December 22, 1931, on

an application flied December 19,1930 by Herman C. Lee.` The punch, shown in Fig. 3, is polygonal in cross section, the number ofV sides depending upon the number of tangs that are desired. It consists of thebody portion I5 by which the punch is held and the upper end of which is of a cross section equal to the `size of perforation desired, usually from .004 to '.0123 square inch in area. 'Ihe body portion terminates in a truncated-pyramid portion IB above which is an extension I1 of the body portion but decreased in cross-section. This portion then terminates in the pyramidal portion I8. When this double-pyramid punch is forced into the foil and absorber the result shown in Fig. 2, is obtained, the upper ends of the tangs being bent' at an angle to the base portion of the tangs.v This angle depends upon the angle of the truncated pyramid portion of the punch. 'I'he foil thereby becomes anchored in the absorber to become attached thereto and integral therewith. In addition, the `foil which extends into the depression in the absorber, lines the side walls thereof. 'I'his is desirable since the metal foil facing may be painted and decorated without having the paint or other decorative material reach the absorber. Furthermore, the absorber -is recessed sufhciently to be practicallyinvisible to the eye. The foil may be enameled or decorated prior to the punching operation to obviate the necessity for decorating afterward. The perforated metal facing may be applied to small or large tiles or tolarge panels or slabs which may be glued, nailed, screwed to or otherwise mounted on the surface to be treated. It is usuallydesirable to extend the foil beyond the face of the tile to cover the edges thereof as shown in Fig. 1 but such edges need not be punched.' 'In some cases the foil may be extended tovcover the back of the pad to completely encase it. Such completed encased pads are used advantageously under certain conditions.

' In an alternative construction but one which is not preferred, the metal is punched separately leaving the tangs projecting outwardly. 'Ihe sound absorber is then pressed onto the tangs."

This method requires stiff metal `or heavier metal to prevent bending of the tangsso that the absorber may be pressed into engagement with from the perforating of said the perforated sheet of metal to force the tangs into saidabsorber the maximum distance.l In another modification the foil isattached, as by gluing, to a thin sheet of non-metallic material il such as kraft paper or thin sheeting. This composite is used. as a facing for the sound absorber, with the lining adjacent the absorber, in the same manner as the foil is used.` Where the tangs anchor the foil sufficiently to thesound absorber, as illustrated in Fig. 2, the lining does not vhave to be glued to the foil but may be inserted loosely. This lining reinforces the foil and hence adds strength to the structure.

I claim:

1. A sound-absorbing construction comprising a self sustaining sound-absorbing material faced with perforated metal foil, the tangs resulting from the perforating of said foil projecting into said material.

2. A sound-absorbing construction comprising a'self-sustaining sound-absorbing material faced with perforated metal foil, said perforations being formed with the foil in place on said material, the pointed tangs resulting from the perforating of said foil projecting into said material, with the points spread apart and being anchored therein to hold said foil in place.

3. A sound-absorbing construction comprising a self-sustaining sound-absorbing material faced with metal foil with polygonal shaped perforations, said perforationsbeing formed with ther Yfoil in place on said material, a multiplicity of hook-like tangs projecting inwardly from the perimeter of each foil perforation; said tangs resulting from said perforating yoperation and projecting into said material.

4. A sound-absorbing construction comprising a self-sustaining sound-absorbing material faced with perforated metal foil glued thereto, said perforations being formed after gluing said foil to said material, the tangs resulting from the perforating of said foil terial. I 5. A sound-absorbing construction comprising a self-sustaining sound-absorbing material faced with perforated metal foil glued thereto, said' perforations being polygonal shape and being formed with said foil glued to said material, the tangs resulting from the perforating off said foil extending inwardly into said material and liningthe side walls of the depression formed in the material by said perforating operation.

6. A sound-absorbing construction comprising a self-sustaining sound-absorbing material faced 'with perforated metal foil,`said metal foil extending beyond the face of said material and facing at least one edge of said material, the tangs resulting from the perforating of said foil -projecting into said material.

'7. A sound-absorbing construction comprising `a self-sustaining sound-absorbing material faced with perforated metal foil, said metal foil ex` tending beyond the face of said material and completely enclosing said material, the. tangs resulting from the perforating of said f oil pro- .jecting into said material.

8. A sound-absorbingconstruction comprising a self-sustaining sound-absorbing material faced with a perforated metal foil, the tangs resulting foil projecting into projecting into said masaidmaterial. said tangs being of predetermined size and shape. i 9. A sound-absorbing construction comprising a self-sustainingl sound-absorbing material faced with reenforced perforated metal foil attached thereto, said reenforeing comprising a sheet of thin material between said foil and said absorber.-

10. A sound-absorbing construction comprising 5 a self-sustaining sound-absorbing material faced with perforated metal foil lined with a sheet of fibrous material, the tangs resulting from the perforating of said foil projecting into said 'sound-absorbing material.

1o 11. The methodof making mound-absorbing construction which comprises facing a soundabsorbing material with a metal foil, perforating said foilhforcing the tangs formed by. said perforating operation into said material and 1li spreading the"'inner ends of said tangs laterally to provide positive engagement therewith.

12. The method of making a sound-absorbing 'construction which comprises gluing a metal foil lface onto a sound-absorbing material, perfoi-ating said foil, forcing the tangs formed by said perforating operation into said material and spreading the inner ends of said tangs laterally to provide positive engagement therewith.

13. A sound absorbing construction consisting of a wall or ceiling surface with a facing attached thereto comprising a self-sustaining sound absorbing material faced with perforated metal foil, the tangs resulting from the perforating of said foil projecting into said material, the surface of the absorbing material opposite to4 that faced with the perforated metal foil being adjacent said wall or ceiling surface.

CHARLES F. BUllISS.` 

